1. Field of the Invention
The present invention relates to a method and apparatus for reducing power consumption in a computer coupled to a network, and more particularly, to a method and apparatus for setting a computer with a power saving function into a power saving mode in which the computer supplies power to those devices that are used in communicating over the network and supplies no power to those devices not used network communications.
2. Description of the Prior Art
Advanced technological developments in computers have necessitated power saving functions, such as hibernation systems and related systems, in order to manage efficiently the supply of power to the various components in computers. A hibernation system may have either of two functions:
An emergency automatic restoration function for storing the present operating state in an auxiliary memory, such as a hard disk, when power to the computer is cut off by a sudden interruption in electric service or by an error on the part of a user. The hibernation system provides for restoring the operating state of the computer to the previous state, according to the contents of the auxiliary memory, when power to the computer is restored.
A power saving function for automatically storing the present operating state in the auxiliary memory and cutting off the power when the computer is idle for a predetermined length of time. The system resumes supplying power and returns the computer to its previous operating state when use of the computer is resumed.
In recent years demand in the personal computer market has expanded for a hibernation system having both an emergency automatic restoration function and a power saving function. Now various kinds of computers and software are also being supplied for various specialized applications. On the other hand, the volume of computation required for a computer to run a specific application has increased because of the requirements of advanced software and the capabilities of advanced hardware. This increase in computational requirements has brought about innovations such as multimedia computers. To compensate for the increased power consumption of multimedia computers, a power saving function is a very important feature of power management for such advanced hardware and software.
A computer having a power saving function has the following general structure. The basic components needed to operate the computer are the central processing unit (CPU), a memory, and a power supply. The computer can also have one or more resources, which can include, for example, an input device such as a keyboard or a mouse for receiving data to be processed by the CPU; an output device such as a monitor for displaying processed data or a printer for printing data; or an input/output device such as a hard disk drive for inputting data to and outputting A data from the CPU. Another resource the computer can have is a network device coupling the computer to a network and allowing the computer to communicate over the network. Various combinations of these and other resources are helpful or necessary for the computer to be used in many applications.
Among these devices and the other constituent elements of the computer, some are required to operate for operation of the computer, while the operation of others is not necessary to operation of the computer. A computer having a power saving function can include a power managing unit that controls the supply of power according to the needs of a user or predetermined criteria. The power managing unit provides for efficient use of power by reducing the use of power by elements of the computer whose operation is not necessary to the user's current activity or when conditions indicate that the computer is presently idle.
A power saving function generally operates in such a computer as follows. When power of the computer is turned on, the CPU and the memory operate. The computer receives from user input a time delay setting that determines how long the computer should operate in an idle state (e.g., without input from the user) before entering into a suspend mode; that is, the time delay setting determines the length of a time delay. The CPU determines whether such an input occurs before the time delay lapses. If an input from an input device occurs before the time delay lapses, then the computer continues to operate in a normal mode. While no input has occurred since the beginning of the time delay, CPU monitors whether the time delay has lapsed. As long as the time delay has not lapsed, the computer continues to operate in its normal mode (i.e., at fill power demand). As soon as the CPU determines that the time delay has lapsed without the occurrence of an input, though, it transmits a mode switching signal to the power managing unit.
The power managing unit regulates the power delivered by the power supply to the various constituent devices of the computer. When the power managing unit receives a mode switching signal and the computer is operating in its normal mode, it responds by setting the computer into the suspend mode and thereby reducing the computer's power consumption.
This approach has provided a certain degree of success in reducing unnecessary power consumption in a computer, but I have found that it contains a basic drawback. Even if a user does not enter an input directly, such as through an input device, during the predetermined time delay the computer's memory or another resource, such as an attached storage device, occasionally can be accessed during the time delay if the computer is coupled to a network. In such a case, the computer should not be set into the suspend mode merely because no direct user input has occurred.